I had an idea recently that initially seemed like a good idea, but got worse and worse the more I thought about it. Even so, I think there's still the germ of something useful in here, and, since I trust you, my dashing readers, I thought I may as well bring it up. It's about using a USB flash drive as a car key. For a vintage car.

As you know, I've had a history with car theft, and while I've taken steps to secure my cars more so now, I sometimes still like to think about some other, weirder ideas. One of the many promo USB flash drives I have is vaguely key-shaped, and that started me thinking about the idea of repurposing a USB drive as a key.

Here's how I think it would work, basically: the USB drive would contain a special file — let's call it the Key File. This would be a text file with a password, a phrase, a huge long 30-digit number, whatever. The point is, it has to be a specific string of characters.

In the car, we'd install a little computer with a USB port— I was thinking of a Raspberry Pi, since it's cheap, can run on as little as 5V, and you could use it for other in-car infotainment stuff. Keep in mind, I'm thinking of a vintage (80s or older, at least) car for all this stuff, since, of course, any modern car will handle this crap better right from the factory.

Advertisement

Anyway, the Raspberry Pi in the car would have connected to its set of general-purpose I/O pins a relay. That relay (or relays, if needed) would be connected to the ignition wires of the car, and when set to closed, would be the electrical equivalent of having the key in and turned to run. We'd also want to wire in a separate starter switch to activate the starter, since we're bypassing the whole ignition lock assembly here.

So, the setup would work like this: you have a USB drive with the Key File. You plug it into the Pi's USB port. The Pi runs a little script to check for the presence of the file, open it, and confirm the string in there matches one you've set. If it does, it sets the relay to closed, and you can start the car with the starter button and go have a blast. If not, no ignition for you, you criminal.

Advertisement

The big advantage here is that you could have a car key that you could easily make any number of copies you wanted. If you loaned someone the car — or you co-owned it with someone — you could just email them the Key File and they could go find the car and drive it. You could change the Key File periodically to keep things more secure.

You could even have that same USB drive open door locks as well, by adding in a simple power lock kit and wiring in a USB jack into the doors. The Pi would then also trip a relay to unlock the doors.

Now, I'm sure most of you have seen huge holes in this plan. Any locking steering column wouldn't be unlocked with this method, so you'd either need to disable that or use a car too old to have one.

Advertisement

It's not terribly secure, really, either, and someone who knew what they were doing could easily disconnect the Pi and just bypass the relay to hotwire the car. You could make that more difficult depending on how you install it, but still.

The more I thought about this, the more I realized this would probably work best in a very specific situation: a group of friends who all co-own one vintage, simple, fun car, like a Bugeye Sprite or something. They could swap key files depending on who gets the car on what day, all by sending a simple email. And, since the car is so old, this minimal security would be an upgrade, and they'd have no steering wheel lock to worry about or anything like that.

Advertisement

Alternately, it could be useful for someone with many vintage cars who hates dealing with physical keys. One USB thumb drive could hold vast numbers of Key Files, so one USB could get you going in any one of your vintage cars that you've equipped.

Beyond these two pretty limited situations, I'm not sure this idea is worth much. But I'm open to hearing creative ideas from you to make it better or situations where it makes sense — what do you think of the USB car key idea?